Looking for silver linings on a day when Britain's economy sinks to new depths of despair might seem perverse. Whatever one thinks of the limitations of GDP as a measure of national prosperity, the fact remains that today's dreadful numbers reflect a society in which more people will lose their jobs and those already out of work will have to wait longer to find it again.

But there is still a reason to cheer – and not just because the economists were once again caught by surprise. Had their consensus forecasts been right and Britain showed modest growth in third quarter, it would have spelt the end for any hope of meaningful long-term change. A tiny rise in GDP might not have made much difference to employment prospects, but symbolically turning the corner would have given enormous political cover to those who argue against doing anything too rash.

Instead, now, perhaps, there is one last chance for a serious debate about the changes that are needed: a decent industrial strategy for example; a rebalancing and move away from over-reliance on financial services, a re-evaluation of tax advantages encouraging indebtedness; real change to income distribution.

Until this morning, we seemed trapped in a surreal bubble of complacency – "we're nearly through the worst, just hold on," was the subliminal message. It is not just the City that is resisting calls for structural change; the economy at large is almost entirely unreformed. Just look at the effect of rising City bonuses on London house prices, and the gap between hype and reality on developing new industries like environmental technology.

As I've said before, I think the government deserves praise for its tactical handling over the crisis: think how much worse today's numbers might have looked without the short-term stimulus measures. I don't believe that the hair-shirt approach to the crisis suggested by the Tories would help – it would just have deepened and prolonged the pain. But where both main parties are woefully failing is in presenting a long-term strategy for how the British economy needs to look in future. Going back to where we were is no longer an option.

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